a large blank white rectangle appears above my Desktop and Tablet breakpoints. It isn’t selectable, doesn’t show in the Layers panel, and isn’t exposed as a node in the project structure. Does anyone know what causes this and how to remove it?

a large blank white rectangle appears above my Desktop and Tablet breakpoints. It isn’t selectable, doesn’t show in the Layers panel, and isn’t exposed as a node in the project structure. Does anyone know what causes this and how to remove it?